The Ship of Theseus - Identity or Are You Still You?

Last time, I said I would be writing about some basic lessons I've learned as I've studied Knowledge.  Today's topic is from basic philosophy is the illustration of The Ship of Theseus. 

Let's begin.

Once upon a time, there was a legendary figure named Theseus who captained a ship.  But really, it doesn't have to be Theseus.  Shoot, it doesn't even have to be a ship, but because this is the canonical way to address this  philosophical question, let's just go with it, OK?  OK.

Theseus has a Ship. Theseus sets out on a Legendary Journey.  It lasts years and years.

Suppose Theseus decides to replace one of the planks which make up the hull of the ship.  He has the old plank taken off, and the new plank replaces it.

Got the picture?  One plank off, one plank on.

After replacing the plank, is Theseus still on The Ship of Theseus?  I'm pretty sure most of us would say he is.  It's the "same ship."  Replacing that one plank does not change the identity of the ship.

OK, then: Over time, Theseus replaces more planks.  And the mast.  And the sails.  Eventually, every piece of the ship has been replaced.  There are no pieces of the ship which were part of the original Ship of Theseus, but Theseus and his crew are still sailing around on a ship.

It looks like the ship which Theseus initially boarded.  It is designed the same.  It has been continuously used as his vessel. 

Is it still the Ship of Theseus?  Certainly it is a ship and it is owned by Theseus, but is it The Ship of Theseus?  Is it the same ship which left port when Theseus started the voyage on his Ship?  When the ship left, its "Identity" was The Ship of Theseus.  How about now, when all its constituent pieces have been replaced?

Now let's go one step further:  When Theseus had each piece of his ship replaced, his trusty first mate had the original pieces sent back home.  The people at home, wanting to honor Theseus, put the pieces back together, each piece in its original spot.  When Theseus returns home, there is a ship awaiting him, built of those pieces.  Is that ship The Ship of Theseus?

This question is part of the literature of Philosophy.  It demonstrates how hard it can be to define some basic concepts.  The Ship of Theseus is often used to demonstrate that "Identity" is not as simple a concept as people think it is -- that "Identity" as most people use the word is far less constant than it is treated.

If you believe that there is something which, at the beginning, could be called The Ship of Theseus, I'd like you to notice that the key word in the phrase is "The."  "The" indicates an identification.  Theseus might have had many ships, but "The" Ship of Theseus denotes the one on which he left for his voyage.  So, if you think there is such a thing as "The" ship on which he left, if you think that entity had a unique Identity, then was there a point at which the ship ceased having that Identity?  At what point did the change happen?  And why would you pick that particular point?

On the other hand, if you think it remained The Ship of Theseus throughout all its changes, then what was the Ship which was built using all the original parts?  If "Identity" is unique, there cannot be two things identified as "The Ship of Theseus."  And if "Identity" is not unique, then what does "Identity" really mean?

This question may seem esoteric and contrived.  So let's bring up the point you will have already anticipated:  Have you always been you?  We know that cells in the body die and are replaced by other cells.  You are your own Ship.

But in contrast to the Ship of Theseus, as your constituent parts were replaced, you changed -- physically.  You grew.  You don't even have the same shape you did when you were younger.  So, are you still you?  Is there any sense in which your "Identity" changed?  Or are you the same you?

"Oh, but I am alive.  I have a soul.  That is what is uniquely 'Me,'" you might say.  Ah, the soul: that's a different philosophical and theological question on its own.  But even if we grant that a person's Identity might be attached to such a thing, what about soulless things -- at the very least, what about inanimate objects?  Do they have Identity?

The very concept of "Identity" is ingrained in most of us.  And yet the discussion of the Ship of Theseus shows us that it's not that simple.

Philosophy is a means by which we can examine some of these ingrained concepts.  And when we examine them, we find out that things are not as simple as we often try to make them. 

In order to start my series of essays, I want to have a few of these basic questions and concepts in place.  But I am by no means the originator of them.  Here's an ancient philosopher who looked at these questions long before I did.

“No man ever steps in the same river twice, for it's not the same river and he's not the same man.”

― Heraclitus

 
So, that's the start.  What's next?  I'll let you know, after I write it.